Antioxidants for polyether polyols and polyurethane foams prepared therefrom are well known and include hindered phenols, phenothiazines, mixtures of hindered phenols with phenothiazines or phosphoric acid, mixtures of 2,6-ditertiarybutyl-4-methyl phenol and a dialkyldiphenyl amine, mixtures of a hindered phenol and 4,4'-bis(.alpha.,.alpha.-dimethylbenzyl)diphenyl amine and mixtures of 2,6-ditertiarybutyl-4-methyl phenol, p,p'-dioctyl diphenyl amine and a phenothiazine.
Because of fluctuation and/or availability of the component materials it is desirable to find ways to decrease the quantity of antioxidant necessary to effectively stabilize the polyol and polyurethane against oxidative degradation and the foams prepared therefrom from scorching.
It has now been unexpectedly discovered that polyether polyols stabilized with a synergistic combination of certain hindered phenols and 4,4'-bis(.alpha.,.alpha.-dimethylbenzyl) diphenyl amine with a phenothiazine compound. The improvement is greater stability to the polyol against oxidative degradation at the same level of antioxidant or reduced levels of antioxidant for the same amount of stability.